Lubrication of a planet-carrier for a mechanical reduction gear of a turbine engine, in particular of an aircraft

ABSTRACT

The invention relates to the lubrication of a planet-carrier for a mechanical reduction gear of a turbine engine, in particular of an aircraft, said planet-carrier comprising a cage defining an internal housing intended to receive a central sun gear with an axis of rotation X, and an annular row of planet gears arranged around the sun gear, said cage comprising two annular walls that are radial with respect to said axis X, and connected to one another at their outer periphery by a cylindrical wall of axis X, at least one of these radial walls comprising orifices for mounting the axes of said planet gears, and the cylindrical wall comprising through-holes for the passage of the gearings of the planet gears so that they may engage with a gearing of the ring gear, which is intended to extend around the planet gears and the cage.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of a mechanical reductiongears for turbine engines, in particular of an aircraft.

TECHNICAL BACKGROUND

The state of the art comprises, in particular, documentsWO-A1-2010/092263, FR-A1-2 987 416, FR-A1-3 041 054, EP-A2-3 109 514,EP-B1-2 844 855,EP-A1-2 615 335, WO-A1-2019/016463 and EP-A2-1 114 949.

The purpose of a mechanical reduction gear is to change the speed andtorque ratio between the input axis and the output axis of a mechanicalsystem.

The new generations of bypass turbine engines, in particular turbineengines with high dilution rates, comprise a mechanical reduction gearthat drives the shaft of a fan. Usually, the purpose of the reductiongear is to transform the “fast” rotational speed of a power turbine intoa slower rotational speed for the shaft driving the fan.

This type of reduction gear comprises a central pinion, termed sun gear,a ring gear and pinions termed planet gears, the latter engaging betweenthe sun gear and the ring gear. The planet gears are maintained by achassis termed planet-carrier. The sun gear, the ring gear and theplanet-carrier are planetary elements because their axes of revolutionare the same as the longitudinal axis X of the turbine engine. Eachplanet gear has a different axis of revolution, evenly distributed overa single operating diameter around the axis of the planetary elements.These axes are parallel with the longitudinal axis X.

There are several reduction gear architectures. According to the stateof the art in the field of bypass turbine engines, reduction gears areof the planetary or epicyclic type. In other similar applications,“differential” or compound architectures can be found.

-   -   In a planetary reduction gear, the planet carrier is fixed, and        the ring gear constitutes the output shaft of the device that        rotates in the opposite direction with respect to the sun gear.    -   In an epicyclic reduction gear, the ring gear is fixed, and the        planet-carrier constitutes the output shaft of the device that        rotates in the same direction as the sun gear.    -   In a differential reduction gear, no element is rotationally        fixed. The ring gear rotates in the opposite direction with        respect to the sun gear and the planet-carrier.

The reduction gears can comprise one or several gearing stages. Thisgearing is achieved in different ways, such as by contact, by frictionand even by magnetic fields.

There are several types of contact gearing, such as straight, helical orherringbone gearings.

The present invention proposes to an improvement of a reduction gearwith a simple, efficient and economical solution to improve thelubrication of its planet-carrier.

SUMMARY OF THE INVENTION

The Invention Features Several Aspects.

According to a first aspect, the invention relates to a planet-carrierfor a mechanical reduction gear of a turbine engine, in particular of anaircraft, said planet-carrier comprising a cage defining an internalhousing intended to receive a central sun gear with an axis of rotationX, and an annular row of planet gears arranged around the sun gear, saidcage comprising two annular radial walls with respect to said axis X,and connected to one another at their outer periphery by a cylindricalwall of axis X, at least one of these radial walls comprising a mountingorifices of the axes of said planet gears, and the cylindrical wallcomprising through-holes of the passage of the gearings of the planetgears so that they may engage with a gearing of the ring gear, which isintended to extend around the planet gears and the cage, characterisedin that it comprises first and second independent lubrication circuits,the first circuit comprising a first oil inlet connected by a firstannular oil chamber extending around the axis X to ducts supplying oilto said axes of the planet gears, and the second circuit comprising ansecond oil inlet connected by a second annular oil chamber extendingaround the axis X to channels supplying oil to the gearings of theplanet gears with the ring gear, and in that said cage, said first andsecond inlets, said ducts, said channels and at least a portion of saidfirst and second chambers are formed of a single part.

The invention thus proposes integrating a major portion of thelubrication circuits in the cage of the planet-carrier, which reducesthe number of parts and facilitates the assembly of the reduction gear.Furthermore, the risks of oil leaks are thus greatly reduced.

The planet carrier according to the invention can comprise one orseveral of the following characteristics, taken individually or incombination:

-   -   said first and second inlets are oriented radially with respect        to said axis X and open radially outwards; they are thus easily        accessible for the purpose of connecting them to oil supply        means,    -   said first and second inlets are located in a same plane that is        perpendicular to said axis X and are at an angle with respect to        one another; they are therefore close to one another and can        pass through a same arm or through different arms of a crankcase        of the turbine engine wherein the reduction gear is integrated        with this planet-carrier,    -   said first and second chambers are arranged adjacent to one        another, one behind the other, along said axis X; this optimises        the compactness and therefore the dimensions of the lubrication        circuits,    -   one of said first and second chambers is located in said plane        and connected to one of said inlets by a radial and rectilinear        drill hole, and the other of said first and second chambers is        located outside of said plane and connected to the other of said        inlets by two drill holes, wherein a first drill hole being        located in said plane and a second drill hole extending at an        angle between the first drill hole and this other chamber; this        also optimises the compactness and therefore the dimensions of        the lubrication circuits; these open drills holes are preferably        sealed by plugs that can be screwed and/or glued.    -   said ducts are formed in one of said radial walls and extend in        a rectilinear manner between said first chamber and a        lubricating cores of the axes of the planet gears; the ducts are        thus formed in the thickness of the radial walls, or in excess        thickness provided in these walls,    -   said channels are formed in one of said radial walls and in said        cylindrical wall, and each is generally L-shaped, extending        between said second chamber and a projecting oil orifices        towards said gearings; the channels are thus formed in the        thickness of the radial and cylindrical walls, or in excess        thickness provided in these walls,    -   said first and second chambers are located on the inner        periphery of one of said radial walls, and are partially        delimited by this radial wall, and partially by an attached        annular distributor comprising a cylindrical wall delimiting,        internally, said chambers and at least an annular partition        axially closing one of said chambers,    -   one of said chambers is connected to at least one nozzle        spraying oil towards said sun gear, said nozzle being integrated        in said distributor; the nozzle is preferably configured to        project oil towards the coupling of the sun gear and its drive        shaft,    -   said second circuit further comprises channels supplying oil to        the gearings of the planet gears with the sun gear,    -   each of said first and second chambers has in cross-section a        general parallelepiped shape.

According to a second aspect, the invention relates to a planet-carrierfor a mechanical reduction gear of a turbine engine, in particular of anaircraft, said planet-carrier comprising a cage defining an internalhousing intended to receive a central sun gear with an axis of rotationX, and an annular row of planet gears arranged around the sun gear, saidcage comprising two annular radial walls that are radial with respect tosaid axis X, and connected to one another at their outer periphery by acylindrical wall of axis X, at least one of these radial wallscomprising a mounting orifices of the axes of said planet gears, and thecylindrical wall comprising through-holes for the passage of thegearings of the planet gears so that they may engage with a gearing ofthe ring gear, which is intended to extend around the planet gears andthe cage, characterised in that it further comprises an annulardistributor of lubricating oil which is formed of a single part andconfigured to be provided and secured to the inner periphery of one ofsaid radial walls, so as to define, together with said radial wall, twoannular chambers which are independent and sealed to oil circulation.

The manufacturing of the oil chambers is simplified since they aredelimited between the cage, on one hand, and by the attacheddistributor, on the other hand. It is indeed easier and morecost-efficient to manufacture the distributor with casting operations orby machining a part, rather than manufacturing the chambers entirely onthe cage, at the assembly site. The distributor has a general shape thatis simple, and it is formed of a single part, which facilitates itsmounting on the cage.

The planet-carrier according to the invention can comprise one orseveral of the following characteristics, taken individually or incombination:

-   -   said distributor comprises a cylindrical wall delimiting        internally said chambers and at least an annular partition        axially closing one of said chambers; the simply shaped        distributor can therefore be cheap to manufacture,    -   said distributor comprises two annular walls that extend        radially outwards from said cylindrical wall and that together        delimit one of said chambers, the other of said chambers being        delimited by one of these partitions and an annular surface        facing the radial wall on which the distributor is attached,    -   the or each partition comprises on its outer periphery an        external cylindrical centring surface on which is formed an        annular groove intended to receive an annular seal intended to        cooperate with the inner periphery of the radial wall on which        the distributor is attached; the cylindrical surfaces therefore        serve a dual purpose of centring but also of sealing, owing to        the fact that they are provided with seals that ensure that the        chambers, and therefore the lubrication circuits, are properly        sealed,    -   said cylindrical wall comprises a cylindrical centring surface        on which an annular groove is formed to receive an annular seal        intended to cooperate with the inner periphery of the radial        wall on which the distributor is attached; this cylindrical        surface also serves a dual centring and sealing purpose,    -   said first and second chambers are arranged adjacent to one        another, one behind the other, along said axis X,    -   said first and second chambers have each a cross-section that        has a general parallelepiped shape,    -   the distributor comprises a flange, or a fixation lugs onto said        cage, by means of screws,    -   an inner cylindrical surface of the inner periphery of said        radial wall on which the distributor is attached, comprises a        protruding annular rib configured to cooperate with said annular        seal,    -   an oil nozzle is connected to one of said chambers, and    -   the oil nozzle is integrated in the distributor, preferably on        said cylindrical wall.

The present invention also relates to a reduction gear for a turbineengine, in particular of an aircraft, comprising a sun gear mountedrotationally secure on a drive shaft around an axis of rotation X, aring gear coaxial with the axis X and a plurality of planet gearsarranged around the axis X, said planet gears being engaged with the sungear and the annular ring gear that extends around the planet gears;said planet gears are movably mounted on the planet-carrier according toone of the features of the invention.

The drive shaft can be a low-pressure shaft of the turbine engine.

The present invention also relates to an aircraft turbine engine,characterised in that it comprises a mechanical reduction gearcomprising a planet-carrier such as described above.

The characteristics of the different aspects of the invention can becombined with one another.

BRIEF DESCRIPTION OF THE FIGURES

Other characteristics and advantages will appear more clearly uponreading the following description of a non-limiting embodiment of theinvention and with reference to the appended drawings, in which:

FIG. 1 is a schematic axial cross-section view of a turbine engine usingthe invention,

FIG. 2 is a partial view showing an axial cross-section of a mechanicalreduction gear,

FIG. 3 is a schematic and perspective view of a mechanical reductiongear according to the invention,

FIG. 4 is a schematic axial cross-section view of the reduction gear ofFIG. 3,

FIG. 5 is a partial, schematic and perspective view of an annulardistributor of lubricating oil,

FIG. 6 is a schematic perspective view of the volumes of the lubricatingoil circuits of the reduction gear of FIG. 3,

FIG. 7a is a schematic axial cross-section view of the reduction gear ofFIG. 3, the cross-section being made in a plane,

FIG. 7b is another schematic axial cross-section view of the reductiongear of FIG. 3, the cross-section being made in a different plane, and

FIG. 7c is another schematic axial cross-section view of the reductiongear of FIG. 3, the cross-section being made in a different plane.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 describes a turbine engine 1 that comprises, conventionally, afan S, a low-pressure compressor 1 a, a high-pressure compressor 1 b, anannular combustion chamber 1 c, a high-pressure turbine 1 d, alow-pressure turbine 1 e, and an exhaust pipe 1 h. The high-pressurecompressor 1 ba nd the high-pressure turbine 1 d are connected by ahigh-pressure shaft 2 and form with the latter a high-pressure (HP)body. The low-pressure compressor 1 aa nd the low-pressure turbine 1 eare connected by a low-pressure shaft 3 and form with the latter alow-pressure (LP) body.

The fan S is driven by a fan shaft 4, which is driven with the LP shaft3 by means of a reduction gear 6. The reduction gear 6 is generally ofthe planetary or the epicyclic type.

Although the following description relates to a planetary reduction gearor an epicyclic reduction gear, it also applies to a mechanicaldifferential in which the three components, i.e. the planet-carrier, thering gear and the sun gear are rotationally mobile, the rotation speedof one of these components depending in particular on the speeddifference of the two other components.

The reduction gear 6 is positioned in the front part of the turbineengine. A fixed structure comprising schematically, in this case, anupstream part 5 a and a downstream part 5 b, constituting the enginecrankcase or stator 5, is arranged to form an enclosure E around thereduction gear 6. This enclosure E is here closed in the upstream partby seals located at the level of a bearing and allowing the passage ofthe fan shaft 4, and in the downstream section by seals located at thelevel of the passage of the LP shaft 3.

FIG. 2 shows a reduction gear 6 that can have different architecturesdepending on whether some parts are fixed or rotating. At the inlet, thereduction gear 6 is connected to the LP shaft 3, for example by means ofinner splines 7 a. The LP shaft 3 drives a planet pinion termed sun gear7. Conventionally, the sun gear 7, of which the axis of rotation is thesame as that of the turbine engine X, drives a series of pinions termedplanet gears 8, these planet gears being evenly distributed over asingle diameter around the axis of rotation X. This diameter is equal totwice the operating distance between the sun gear 7 and the planet gears8. The number of planet gears 8 generally ranges from three to seven forthis type of application.

The set of the planet gears 8 is held by a chassis termed planet-carrier10. Each planet gear 8 rotates about its own axis Y and engages with thering gear 9.

At the output, this provides:

-   -   in an epicyclic configuration, the planet gears 8 rotationally        drive the planet-carrier 10 about the axis X of the turbine        engine. The ring gear is secured to the engine crankcase or the        stator 5 by means of a ring-carrier 12 and the planet-carrier 10        is secured to the fan shaft 4.    -   in a planetary configuration, the planet gears 8 are held by a        planet-carrier 10 that is secured to the engine crankcase or the        stator 5. Each planet gear drives the ring gear, which is        supported on the fan shaft 4 by means of a ring-carrier 12.

Each planet gear 8 is mounted free to rotate by means of a bearing 11,for example a roller bearing or a hydrodynamic bearing. Each bearing 11is mounted on one of the axes 10 b of the planet-carrier 10 and all theaxes are positioned with respect to one another by means of one orseveral structural chassis 10 a of the planet-carrier 10. The number ofaxes 10 b and of bearings 11 is equal to the number of planet gears. Foroperating, assembly, manufacturing, control, repairs or replacementreasons, the axes 10 b and the chassis 10 a can be divided into severalparts.

For the reasons mentioned above, the gearing of a reduction gear can bedivided into several helices, each with a median plane P. In thisexample, we will detail the operation of a reduction gear with severalhelices and with a ring gear divided into two half-ring gears:

-   -   a front half-ring gear 9 a consisting of a rim 9 aa and an        attachment half-flange 9 ab. The rim 9 aa comprises the front        helix of the gearing of the reduction gear. This front helix        engages with that of the planet gear 8, which in turn engages        with that of the sun gear 7.    -   a rear half-ring gear 9 b consisting of a rim 9 ba and an        attachment half-flange 9 bb. The rim 9 ba comprises the rear        helix of the gearing of the reduction gear. This rear helix        engages with that of the planet gear 8, which in turn engages        with that of the sun gear 7.

In the case of herringbone gearings, if the helix widths vary betweenthe sun gear 7, the planet gears 8, and the ring gear 9 because ofoverlapping gearings, they are all centred on a median plane P1 for thefront helixes, and on another median plane P2 for the rear helixes. Theother figures relate to the case of a bearing with two rows of rollers.

The attachment half-flange 9 ab of the front half-ring gear 9 a and theattachment half-flange 9 bb of the rear half-ring gear 9 b form theattachment flange 9 c of the ring gear. The ring gear 9 is secured tothe ring-carrier 12 by assembling the attachment flange 9 c of the ringgear to the attachment flange 12 a of the ring-carrier by means of abolted assembly for example.

The arrows of FIG. 2 show the path of the oil in the reduction gear 6.The oil arrives in the reduction gear 6 from the stator part 5 in adistributor 13 by different means that are not detailed in this view asthey are specific to one or several types of architecture. Thedistributor 13 is divided into two parts, and generally each part hasthe same number of planet gears. The purpose of the injectors 13 a is tolubricate the gearings and the purpose of the arms 13 b is to lubricatethe bearings. The oil is brought to the injector 13 a, exiting at itsend 13 c to lubricate the gearings. The oil is also brought to the arm13 b and circulates through the supply intake 13 d of the bearing. Theoil then circulates through the axis 10 b or in one or several bufferzones 10 c to then exit through the orifices 10 d in order to lubricatethe bearings 11 of the planet gears 8.

FIGS. 3 to 7 show an embodiment of a reduction gear 6 comprising severalaspects of the invention.

One of these aspects relates to the lubricating oil distributor 13′ andanother relates to the lubricating oil circuits 15 a, 15 b of thereduction gear 6.

The reduction gear 6 of the FIGS. 5 and following is similar to thatdescribed above and comprises a planet-carrier 10 attached with a cage14.

The cage 14 comprises two radial annular walls 14 a, 14 b that extendaround the axis X, these walls 14 a, 14 b being parallel and beingrespectively a front radial wall 14 a and a rear radial wall 14 b. Thewalls 14 a, 14 b are connected to one another at their outer peripheriesby a cylindrical wall 14 c. The walls 14 a, 14 b and 14 c are morevisible in FIGS. 7a to 7 c.

The cage 14 defines an internal housing intended to receive the centralsun gear 7 with an axis of rotation X, and the annular row of planetgears 8 arranged around the sun gear 7.

At least one of the radial walls 14 a, 14 b (the front wall 14 a in theexample shown in FIGS. 7a to 7c ) comprises orifices 14 aa for mountingthe axes 10 b of the planet gears 8, and the cylindrical wall 14 ccomprises through-holes 14 c a for the passage of the gearings of theplanet gear 8 so that they may engage with the gearing of the ring gear9 intended to extend around the planet gears 8 and the cage 14.

The orifices 14 aa are regularly distributed about the axis X. Each ofthe walls 14 a, 14 b further comprises a central orifice 14 ab, 14 baaligned with the axis X. The walls 14 a, 14 b can further be connectedto one another by another cylindrical wall 14 d extending over the innerperiphery of the walls 14 a, 14 b, around the orifices 14 ab, 14 ba.This wall 14 d is visible in FIG. 7 b.

The reduction gear 6 comprises two lubrication circuits 15 a, 15 b thatare independent, the oil volumes of these circuits being visible in FIG.6.

The first circuit 15 a comprises a first oil inlet 15 aa connected by afirst annular oil chamber 15 ab extending about the axis X to ducts 15ac supplying oil to the axes 10 b of the planet gears 8.

The second circuit 15 b comprises a second oil inlet 15 ba connected bya second annular oil chamber 15 bb extending about the axis X tochannels 15 bc supplying oil to the gearings of the planet gears 8 withthe ring gear 9. The second circuit 15 b can further comprise channels15 bd supplying oil to the gearings of the planet gears 8 with the sungear 7.

As can be seen in the drawings, the inlets 15 aa, 15 ba, the ducts 15ac, the channels 15 bc, 15 bd, and at least a portion of the chambers 15ab, 15 bb are integrated in the cage 15, i.e. they are not formed by orin the parts attached on the cage but are an integral part of the cage.

The inlets 15 aa, 15 ba are oriented radially with respect to said axisX and open radially outwards for the purpose of their connection to oilsupply means. These inlets 15 aa, 15 ba are located in a same plane P3,perpendicular to the axis X and at an angle with respect to one anotherin this plane P3, about the axis X (FIGS. 7a and 7b ).

The chambers 15 ab, 15 bb are arranged adjacent to one another, onebehind the other, along said axis X. They each have a generalparallelepiped shape in the example shown. One of these chambers,specifically the front chamber 15 bb in the example shown, is located inthe abovementioned plane P3 and is connected to the inlet 15 ba by aradial and rectilinear drill hole 16 a formed in the rear radial wall 14b (FIGS. 7b and 7c ). The other chamber 15 ab is located outside of theplane P3 (in this case behind the plane) and is connected to the otherinlet 15 aa by two drill holes, a first drill hole 16 b being located inthe plane P3 and a second drill hole 16 c extending at an angle from thefirst drill hole 16 b to the chamber 15 ab (FIG. 7a ).

The ducts 15 ac are formed in the rear radial wall 14 b and extend in arectilinear manner and at a slight angle between the chamber 15 ab andthe cores 17 supplying oil to the planet gears 8 (FIG. 7a ).

The channels 15 bc are formed in the rear radial wall 14 b and in thecylindrical wall 14 c (FIG. 7c ). They each have a general L shape andeach comprises a rectilinear and radial branch that extends in the wall14 b from the chamber 15 bb, and an axial rectilinear branch extendingin the wall 14 c to the orifices 15 bc 1 projecting oil towards thegearings of the planet gears 8 with the ring gear 9 (FIGS. 7c and 6).

The channels 15 bd are formed in the wall 14 d and extend from thechamber 15 bb to the orifices 15 bd 1 for projecting oil towards thegearings of the planet gears 8 with the sun gear 7 (FIGS. 6 and 7 b).

The chambers 15 ab, 15 bb are located at the inner periphery of the wall14 b, and are partially delimited by this radial wall, and partially bythe distributor 13′ attached on this wall and secured thereto by meansof screws 18 (FIGS. 3 and 4).

The inner periphery of the wall 14 b comprises a cylindrical wall 19oriented towards the rear and comprising an internal cylindrical surface19 a on which open the radially internal ends of the drill holes 16 a,16 c, of the ducts 15 ac, and of the channels 15 bc (FIGS. 7a to 7c ). Arear radial surface 19 b of the wall 14 b extends from the centralorifice 14 bb of the wall 14 b to the surface 19 a. The channels 15 bdopen axially in the downstream direction onto the surface 19 b (FIG. 7b).

The distributor 13′ has a generally annular shape and is formed of asingle part. It comprises a cylindrical wall 13 a delimiting internallythe chambers 15 ab, 15 bb, the chambers being intended to be delimitedexternally by the surface 19 a of the wall 14 b when the distributor 13′is mounted coaxially on the wall 14 b by engaging it inside the edge andthe orifice 14 bb of the wall 14 b.

The distributor 13′ comprises two annular partitions 13 b, 13 c that aresubstantially radial in the example shown. One of the partitions 13 cextends radially outwards from the rear end of the wall 13 a and issupported radially, in a sealed manner, by the surface 19 a, here at therear end of the edge 19.

Thy cylindrical wall 13 a of the distributors 13′ has a front end thatis supported radially, in a sealed manner, by the peripheral edge of theorifice 14 bb. The partition 13 b extends radially outwards, at adistance from the upstream end of the wall 13 a and of the partition 13b, and is also supported radially, in a sealed manner, by the surface 19a.

Each sealed support is achieved, in the example shown, by an O-ring thatis arranged in an annular groove 20 of the outer periphery of thepartition 13 b, 13 c, or of the front end of the wall 13 a, and thatcooperates by support and elastic deformation with the radial wall 14 bor its edge 19.

To facilitate the centring of the distributor 13′ and the forming ofgrooves 20 on the partitions 13 b, 13 c, the latter can be oversized attheir outer peripheries and each can comprise a centring cylindricalsurface on which is formed the groove 20 receiving a seal. Furthermore,to facilitate the mounting of the distributor 13′ by an axialtranslational movement in the orifice 14 bb and the edge 19, the sealsupported by the partition 13 b can cooperate with an annular rib 19 dprotruding on the surface 19 a, as can be seen in FIGS. 7b and 7 c.

It should be understood that the chamber 15 bb is closed by thedistributor 13′ and delimited between a front annular portion of thesurface 19 a, the surface 19 b, a front annular portion of the wall 13a, and the partition 13 c. The chamber 15 ab is closed by thedistributor 13′ and delimited between a rear annular portion of thesurface 19 a, a rear annular portion of the wall 13 a, and the partition13 b, 13 c.

The chambers 15 ab, 15 bb are independent since they do not communicatewith one another.

The distributor 13′, and in particular its partition 13 b, comprise anannular flange 21 that extends radially outwards and comprises orifices22 for the passage of screws 18 that are screwed into the tappedorifices of the wall 14 b of the cage.

The distributor 13′ further comprises, protruding on the internalcylindrical surface of its wall 13 a, an oil nozzle 23 that is connectedto the front chamber 15 bb (FIGS. 5 and 7 a). This nozzle 23 isconfigured to project oil on the coupling of the sun gear 7 and thelow-pressure shaft 3 of FIG. 2.

The nozzle 23 is also advantageously integrated in the distributor 13′,as can be seen in the example shown.

The oil circuits 15 a, 15 b are advantageously configured to be fluidly,connected at the level of their inlets and their possible outlets, bymale-female fittings, i.e. by connections that only require fittingalong an axial direction of motion of a male connector into a femaleconnector. Even if a connector is presented in the following descriptionas being male and intended to engage with a female connector, it canalternatively be replaced by a female connector intended, therefore, toengage with a male connector, and conversely. The sealing of themale-female connectors can be provided by O-rings or similar seals.

With regard to the inlets 15 aa, 15 ba, each one comprises a femaleconnector in the example shown, intended to receive the male connectorof an oil supply pipe (FIGS. 6 to 7 c).

Regarding the oil outlets, excluding the orifices 15 bc 1, 15 bd 1 forthe projection of oil, they are located at the radially external ends ofthe ducts 15 ac (FIGS. 6 and 7 a).

As can be seen in FIG. 7a , each of the outlets of the ducts 15 accomprises a female connector 15 ac 1 in the example shown, intended toreceive the male connector of one of the cores 17. These connectors 15ac 1 are oriented axially, all in the same direction, which here isforwards.

The purpose of the cores 17 is to lubricate and cool the axes 10 b ofthe planet gears 8.

In the example embodiment shown, each axis 10 b is guided by a doubleroller bearing 11, i.e. with double rows of rollers 11 a. The two rowsextend about a single axis that corresponds to the axis, marked Y of theaxis 10 b of the planet gear 8. The application can also comprise morethan two rows.

Conventionally, the rollers are guided in tracks defined by inner andouter rings. A feature here is that the inner rings for guiding therollers 11 a are integrated in the axis 10 b. The outer periphery of theaxis 10 b therefore comprises cylindrical tracks 11 b for the rolling ofthe rollers 11 a, each track 11 b being axially delimited by annularribs 11 c, the purpose of which is to guide the cages 11 d maintainingthe rollers 11 a. Furthermore, FIGS. 7a to 7c show that the outer ringsare integrated at the inner periphery of the planet gears 8. The innerperiphery of the planet gears 8 thus comprises cylindrical tracks 8a forrolling the rollers 11 a.

The inner periphery of the axis 10 b comprises an internal cylindricalsurface 10 e intended to be covered by the core 17.

This core 17 essentially comprises three parts, i.e. a cylindricalportion 17 a, a disc 17 b and a ring 17 c. The core 17 is in this caseformed from a single part, but this characteristic is not limiting.

The portion 17 a extends along the axis Y and comprises an inner duct,termed first duct 17 a 1, that extends along the axis Y over nearly theentire length of the portion 17 a in the example shown.

The portion 17 a has an axial (rear) end forming the abovementioned maleconnector, and an opposite end (front) connected to the centre of thedisc 17 b, the outer periphery of which is connected to the ring 17 c.The disc 17 b extends in a plane that is substantially perpendicular tothe axis Y and comprises an inner duct, termed second duct 17 b 1, thatextends radially from the first duct 17 a 1 to the external annularsurface of the disc 17 b.

The disc 17 b is substantially connected to the middle of the ring 17 c(along the axis Y), so that the second duct substantially opens onto themiddle of the ring 17 c. The disc 17 b could comprise several secondradial ducts 17 b 1 regularly spaced about the axis Y.

The ring 17 c extends about the axis Y and delimits with the internalcylindrical surface of the axis 10 b an annular cavity 22 for thecirculation of oil and for the supply of the orifices 10 d transportingthe oil to the bearing 11 and to the cages 11 d, these orifices beingvisible in FIG. 2.

In use, the oil reaches the chambers 15 ab, 15 bb through the inlets 15aa, 15 ba and the drill holes 16 a, 16 b and 16 c. The oil in thechamber 15 ab supplies the cores 17 through the ducts 15 ac for thepurpose of lubricating the bearing 11. The oil in the chamber 15 bbsupplies the channels 15 bc, 15 bd for the purpose of lubricating thegearings. Oil is further projected by the nozzle 23 onto the coupling ofthe sun gear 7 with the LP shaft 3.

1. Planet-carrier for a mechanical reduction gear of a turbine engine, in particular of an aircraft, said planet-carrier comprising a cage defining an internal housing intended to receive a central sun gear with an axis of rotation X, and an annular row of planet gears arranged around the sun gear, said cage comprising two annular radial walls with respect to said axis X, and connected to one another at their outer periphery by a cylindrical wall) of axis X, at least one of these radial walls comprising a mounting orifices of the axes of said planet gears, and the cylindrical wall comprising through-holes of the passage of the gearings of the planet gears so that they may engage with a gearing of the ring gear, which is intended to extend around the planet gears and the cage, wherein it comprises first and second independent lubrication circuits, the first circuit comprising a first oil inlet connected by a first annular oil chamber extending around the axis X to ducts supplying oil to said axes of the planet gears, and the second circuit comprising an second oil inlet connected by a second annular oil chamber extending around the axis X to channels supplying oil to the gearings of the planet gears with the ring gear, and in that said cage, first and second inlets, said ducts, said channels and at least a portion of said first and second chambers are formed of a single part.
 2. Planet-carrier according to claim 1, wherein said first and second inlets are oriented radially with respect to said axis X and open radially outwards.
 3. Planet-carrier according to claim 2, wherein said first and second inlets are located in a same plane that is perpendicular to said axis X and are at an angle with respect to one another.
 4. Planet-carrier according to claim 1, wherein said first and second chambers are arranged adjacently, one behind the other, along said axis X.
 5. Planet-carrier according to claim 3, wherein one of said first and second chambers is located in said plane and connected to one of said inlets by a radial and rectilinear drill hole, and the other of said first and second chambers is located outside of said plane and connected to the other of said inlets by two drill holes, wherein a first drill hole being located in said plane and a second drill hole extending at an angle between the first drill hole and the other chamber, and wherein said first and second chambers are arranged adjacently, one behind the other, along said axis X.
 6. Planet-carrier according to claim 1, wherein said ducts are formed in one of said radial walls and extend in a rectilinear manner between said first chamber and a lubricating cores of said axes of the planet gears.
 7. Planet-carrier according to claim 1, wherein said channels are formed in one of said radial walls as well as in said cylindrical wall and each has a general L shape extending between said second chamber and the orifices projecting oil towards said gearings.
 8. Planet-carrier according to claim 1, wherein said first and second chambers) are located on the inner periphery of one of said radial walls, and are partially delimited by this radial wall, and partially by an attached annular distributor comprising a cylindrical wall delimiting, internally, said chambers and at least an annular partition axially closing one of said chambers.
 9. Planet-carrier according to claim 8, wherein one of said chambers is connected to at least one nozzle spraying oil towards said sun gear, said nozzle also being integrated in said distributor.
 10. Planet gear according to claim 1, wherein said first and second chambers each have in cross-section a general parallelepiped shape.
 11. Planet-carrier according to claim 1, wherein said second circuit further comprises channels supplying oil to the gearings of the planet gears with the sun gear.
 12. Reduction gear for a turbine engine, in particular of an aircraft, comprising a sun gear mounted rotationally secure on a drive shaft around an axis of rotation X, an annular ring gear coaxial with the axis X and a plurality of planet gears arranged around the axis X, said planet gears being engaged with the sun gear and the annular ring gear that extends around the planet gears, wherein said planet gears are mounted mobile on the planet-carrier according to claim
 1. 13. Turbine engine of an aircraft wherein it comprises a mechanical reduction gear comprising a planet-carrier according to claim
 1. 